The technologies to thaw frozen sushi with microwave of, for example, a microwave oven have been disclosed in Japanese Patent Publication (JP) 8-180790A, JP 9-98888A, JP 10-210960A, JP11-8058A, JP 11-251054A, JP 11-307239A, and JP 2002-223711A.
Any of the known technologies is placing frozen sushi on a disc-like thawing panel and irradiating it with microwave.
It is desired to thaw frozen sushi such that “shari” (a ball of vinegared rice) is moderately warm and “neta” (a slice of fish or other ingredient) is cold.
In the aforementioned conventional technologies, the intensity distribution of microwave is controlled to heat the shari rather than the neta with microwave. However, it is not easy to thaw frozen sushi on the thawing panel always to have moderately warm shari and cold neta. Inconveniently, neta is sometimes also warm.